Environmental control system with humidity control and method

Abstract

An environmental control system has a controller (10) which causes heating apparatus (12A) or ventilation apparatus (12B) to operate through thermostatic dead zone temperature ranges, in response to excessive relative humidity. In the event the heating apparatus (12A) is actuated in response to falling temperatures, ventilation, previously called for by excess humidity, is terminated to prevent inefficiency due to concurrent heating and ventilating. After fresh air of relative lower humidity is introduced by ventilation, the fresh air is heated to further reduce the relative humidity.

What is claimed is: 
     
       1. In an environmental control system having heating apparatus and temperature responsive means for controlling the heating apparatus, a humidity controlled sub-system, comprising: means for sensing the relative humidity;   a ventilation system; and   means for actuating the ventilation system in response to the relative humidity exceeding a preselected value until the heating apparatus is actuated by said temperature responsive means to increase the temperature and thereby reduce the relative humidity; and in which   said heating apparatus controlling means includes a humidity sensor and a humidistatic circuit responsive to the humidity sensor for producing a binary actuation signal in response to sensed humidity.   
     
     
       2. The environmental control system of claim 1 in which said ventilation system comprises moveable ventilation louvers and means for causing said louvers to open and close when actuated and deactuated, respectively. 
     
     
       3. The environmental control system of claim 1 in which said ventilation actuating means includes a logic circuit connected with and responsive to both a humidity sensor circuit and an electronic thermostatic circuit. 
     
     
       4. The environmental control system of claim 3 in which said ventilation actuation circuit includes means responsive to an output signal from said logic circuit to actuate said ventilating apparatus until said heating, apparatus is actuated. 
     
     
       5. The environmental control system of claim 1 in which said heating apparatus controlling means includes a heater actuation circuit responsive to said binary actuation signal to actuate the heating apparatus. 
     
     
       6. The environmental control system of claim 1 in which said heater controlling means includes a heater actuation circuit responsive to signals from either a humidity sensor circuit or an electronic thermostatic circuit to actuate the heating apparatus. 
     
     
       7. A method of controlling the relative humidity within a controlled space, comprising the steps of: sensing the temperature within the controlled space;   controlling a heating apparatus in accordance with sensed temperature to maintain a preselected temperature range within the controlled space;   actuating a ventilation system to introduce fresh air into the controlled space;   deactuating said ventillation system in response to actuation of the heating apparatus in accordance with sensed temperature;   establishing a dead zone temperature range over which said heating controlling means does not call for actuation of the heating apparatus; and   causing said heating apparatus to continue heating through said dead zone in response to the sensed relative humidity.   
     
     
       8. The method of claim 7 in which said fresh air is of lesser absolute humidity than the air it replaces within the controlled space and including the step of heating the fresh air to further reduce the relative humidity within the controlled space.